Re: [Xenomai-help] Signals

[Jan Kiszka <jan.kiszka@domain.hid>]

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Kent Borg wrote:
> Thanks for the news that gdb should just work.
> 
> Now I am wondering about signals.  I want to be able to send a regular
> Linux signal to a userland realtime process.  Do I use the regular
> signal() to install a signal handler?  When would I use
> rt_task_catch() and rt_task_notify()?

Those function are - in contrast to what to doc states - not yet
available in userspace. So far Xenomai is lacking the infrastructure to
deliver hard-RT signals to userspace threads, only the Linux signals are
passed as usual.

> 
> What about multiple threads?  I have 2 threads running.  It seems that
> the thread that called signal() is the one landing in the handler
> routine.  I would like to set some flags for the second thread to see,
> so it can cleanup things before quiting, but it seems that my second
> thread isn't running after I send the signal.  I also think I am
> corrupting something, because if I set up a loop that launches and
> kills my program, my machine freezes up after a dozen cycles.  I
> commented out most of my guts and it still freezes up.

Signals in multithreaded applications are tricky in general, even
without Xenomai. You may try to play with pthread_kill and
pthread_sigmask to control which thread receives a specific signal.

When the signal receiver is a Xenomai thread, the usual things happen:
blocking on RT-resources is cleared, the thread is migrated to secondary
mode, and the signal handler is invoked as one expects.

Jan


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